Update `Scope` of contextmenu / keyboard shortcut items to include a `focusedNode` property

[maribethb]

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Problem

Keyboard shortcuts and context menu items need to know which item was focused, and this may not be just a block/workspace/comment. It could be any focusable item.

Request

1. Add a focusedNode (open to naming suggestions) property to the Scope type.
2. Update the callers of the getContextMenuOptions function to include the property when they call this method. Continue setting the other properties if relevant for backwards compatibility.

Alternatives considered

No response

Additional context

No response

[maribethb]

The remaining work here is just to remove this cast to any once BlockSvg and other Blockly items implement IFocusableNode https://github.com/google/blockly/blob/c6e58c4f92dece0b3da241e0cc31ea09f922b7ce/core/contextmenu_registry.ts#L158